External wounds and concomitant bleeding are common injuries in both civilian and military life. Scratches, cuts, abrasions and the like cause breakage of protective tissue and blood vessels, resulting in the flow of blood out of its normal passageways. This flow of blood washes foreign material out of the wound, and the blood clots to seal the area. Clotting prevents migration of materials into the wound area and into the body of the affected individual. This reduces the likelihood of subsequent infection of the wound.
Historically, hemorrhaging is the single major cause of death among those killed in action—as many as 25% of battle casualties that result in early death could benefit from hemorrhage control. In addition, trauma is the leading cause of death for persons 1–44 years of age.
Penetrating missiles cause 90% of combat trauma, versus 25–50% in the civilian sector, and blast, thermal, and blunt trauma account for the remaining 10%. On the battlefield, a wound must be successfully dressed and staunched in one hour, or the victim dies. Exsanguination accounts for most of the post-trauma mortality from deep penetrating wounds, particularly those of the hip. Twenty-five percent of all battlefield mortality is caused by this type of wound.
There are many different treatments for wounds available, most of which involve directly applying pressure to the wounded area and the disposition of an absorptive material or bandage to the wound surface. Direct application of pressure acts to close blood vessels in the area to reduce blood flow; absorb blood flow that is likely to contain foreign material; and to stabilize movement of the blood so that clotting may commence. The disposition of a bandage further absorbs blood flow; provides a barrier to further infection of the wound; and protects the nascent clot while it is still fragile. Ideally, a bandage can also provide antimicrobial or other healing material to the wound surface.
Newer technology for management of wounds includes chemical bandages, polymeric film-forming material applied to the wound area. These products include cyanoacrylate polymers, made with natural coagulants, such as thrombin, prothrombin, and the like. The drawbacks encountered with such formulations, however, include tissue irritation from the cyanoacrylate and the fact that the use of human or animal-derived proteins may be dangerous due to the risk of viral or prion infection, as well as allergic reactions.
For major bleeding incidents, such as those that may be encountered in combat, hemostatic pressure bandages, such as described by Bell, U.S. Pat. No. 5,800,372 can be used to initiate clotting and arrest hemorrhages. However, the collagen used in such dressings is obtained from bone, which may be contraindicated due to the infection risks aluded to above.
Additionally, a hemostatic bandage currently being developed by the Red Cross (but not yet approved by the FDA) has the drawback that it may trigger allergic reactions. This bandage also uses human blood proteins, thus taxing an already overburdened blood supply. It also lacks durability.
Other developments include a chitosan bandage that has been developed which uses shrimp cell chitin to halt severe bleeding, manufactured by HemCon, Inc. of Portland, Oreg. The bandage allows the wound to quickly form a strong, adherent clot, so that the patient can be transported, and offers rapid, strong adhesion to the injury site to heal the wound.
Once a wound has been treated, there may be a continuing need to apply medication during the healing process. Presently, this is done by continual wound maintenance involving cleaning, debridement where needed, administration of medication and re-bandaging. This process may cause discomfort, time and expense, and may result in inefficient or impaired healing.
Thus, there is a need in the art for a bandage that swiftly provides an anticoagulant when needed in the case of severe bleeding or hemorrhage. It would be further desirable if the same bandage was also capable of continuously delivering medication to the wound during the healing process.